近日，美国佐治亚理工学院的Peter J. Yunker及其研究团队取得一项新进展。经过不懈努力，他们揭示细菌菌落生长的生物物理基础。相关研究成果已于2024年7月9日在国际知名学术期刊《自然—物理学》上发表。

该研究团队表明细菌菌落的水平膨胀率，是通过生物膜边缘的接触角与垂直膨胀强烈耦合的。利用白光干涉测量法，研究人员测量了生长菌落的三维表面形态，发现小菌落被很好地描述为球冠。在后来的时间里，营养物质的扩散和吸收阻止了高群落中心的指数增长。研究人员进一步表明，一个连接垂直和水平生长动力学的简单模型可以再现所观察到的现象，从而有力证明球形冠层的形成，实为扩散限制生长这一生物物理过程所引发的自然结果。

据悉，细菌通常附着在表面上，生长密集的群落，称为生物膜。随着生物膜的生长，它们在表面膨胀，增加了它们的表面积和获取营养的途径。因此，生物膜的整体生长速率直接取决于其范围膨胀速率。水平和垂直生长之间的直接权衡影响范围膨胀速率，至关重要的是，影响整体生物膜的生长速率。人们对水平和垂直生长之间的生物物理联系仍然知之甚少，这在很大程度上是因为很难从小长度尺度到宏观尺度，以足够的空间和时间分辨率分辨生物膜形状。

附：英文原文

Title: The biophysical basis of bacterial colony growth

Author: Pokhrel, Aawaz R., Steinbach, Gabi, Krueger, Adam, Day, Thomas C., Tijani, Julianne, Bravo, Pablo, Ng, Siu Lung, Hammer, Brian K., Yunker, Peter J.

Issue&Volume: 2024-07-09

Abstract: Bacteria often attach to surfaces and grow densely packed communities called biofilms. As biofilms grow, they expand across the surface, increasing their surface area and access to nutrients. Thus, the overall growth rate of a biofilm is directly dependent on its range expansion rate. A direct trade-off between horizontal and vertical growth impacts the range expansion rate and, crucially, the overall biofilm growth rate. The biophysical connection between horizontal and vertical growth remains poorly understood, in large part due to the difficulty in resolving the biofilm shape with sufficient spatial and temporal resolutions from small length scales to macroscopic sizes. Here we show that the horizontal expansion rate of bacterial colonies is strongly coupled to vertical expansion via the contact angle at the biofilm edge. Using white light interferometry, we measure the three-dimensional surface morphology of growing colonies, and find that small colonies are well described as spherical caps. At later times, nutrient diffusion and uptake prevent the tall colony centre from growing exponentially. We further show that a simple model connecting vertical and horizontal growth dynamics can reproduce the observed phenomena, suggesting that the spherical cap shape emerges due to the biophysical consequences of diffusion-limited growth.

DOI: 10.1038/s41567-024-02572-3

Source: https://www.nature.com/articles/s41567-024-02572-3